A reader is a device that can be used to communicate with credential devices (e.g., cards, fobs, tags, phones, etc.) in access control systems, credential systems, and other systems. The reader may read data from the credential and the reader may write data to the credential.
Generally, the credential device is an active or passive radio frequency (RF) communication device that can wirelessly communicate with various devices in the system (e.g., readers, access control devices, etc.). Passive credential devices rely on another device to supply power to the passive credential device by virtue of an excitation signal, whereas active credential devices supply their own power. Common passive credential devices include proximity cards, which communicate via data signals transmitted at a nominal carrier frequency of 125 kHz, and smartcards, which communicate via data signals transmitted at a nominal carrier frequency of 13.56 MHz.